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McCabe complexity checker
=========================
Ned's script to check McCabe complexity.
This module provides a plugin for flake8, the Python code checker.
Installation
------------
You can install, upgrade, or uninstall mccabe with these commands::
$ pip install mccabe
$ pip install --upgrade mccabe
$ pip uninstall mccabe
Standalone script
-----------------
The complexity checker can be used directly::
$ python -m mccabe --min 5 mccabe.py
("185:1: 'PathGraphingAstVisitor.visitIf'", 5)
("71:1: 'PathGraph.to_dot'", 5)
("245:1: 'McCabeChecker.run'", 5)
("283:1: 'main'", 7)
("203:1: 'PathGraphingAstVisitor.visitTryExcept'", 5)
("257:1: 'get_code_complexity'", 5)
Plugin for Flake8
-----------------
When both ``flake8 2+ and mccabe`` are installed, the plugin is
available in flake8::
$ flake8 --version
2.0 (pep8: 1.4.2, pyflakes: 0.6.1, mccabe: 0.2)
By default the plugin is disabled. Use the ``--max-complexity`` switch to
enable it. It will emit a warning if the McCabe complexity of a function
is
higher than the provided value::
$ flake8 --max-complexity 10 coolproject
...
coolproject/mod.py:1204:1: C901 'CoolFactory.prepare' is too complex
(14)
This feature is quite useful for detecting over-complex code. According to
McCabe,
anything that goes beyond 10 is too complex.
Flake8 has many features that mccabe does not provide. Flake8 allows users
to
ignore violations reported by plugins with ``# noqa``. Read more about this
in
[their documentation
].
To silence violations reported by mccabe, place your ``# noqa: C901`` on
the function definition line, where the error is reported for (possibly a
decorator).
Links
-----
* Feedback and ideas: http://mail.python.org/mailman/listinfo/code-quality
* Cyclomatic complexity: http://en.wikipedia.org/wiki/Cyclomatic_complexity
* Ned Batchelder's script:
http://nedbatchelder.com/blog/200803/python_code_complexity_microtool.html
* McCabe complexity: http://en.wikipedia.org/wiki/Cyclomatic_complexity
Changes
-------
0.7.0 - 2021-01-23
``
* Drop support for all versions of Python lower than 3.6
* Add support for Python 3.8, 3.9, and 3.10
* Fix option declaration for Flake8
0.6.1 - 2017-01-26
``
* Fix signature for ``PathGraphingAstVisitor.default to match the signature
for ASTVisitor``
0.6.0 - 2017-01-23
``
* Add support for Python 3.6
* Fix handling for missing statement types
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